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BS67F340/BS67F350/BS67F360/BS67F370
Enhanced Touch A/D Flash MCU with LCD Driver
BS67F340/BS67F350/BS67F360/BS67F370
Enhanced Touch A/D Flash MCU with LCD Driver
TM Operation
The different types of TM offer a diverse range of functions, from simple timing operations to PWM
signal generation. The key to understanding how the TM operates is to see it in terms of a free
running count-up counter whose value is then compared with the value of pre-programmed internal
comparators. When the free running count-up counter has the same value as the pre-programmed
comparator, known as a compare match situation, a TM interrupt signal will be generated which
can clear the counter and perhaps also change the condition of the TM output pin. The internal TM
counter is driven by a user selectable clock source, which can be an internal clock or an external pin.
TM Clock Source
The clock source which drives the main counter in each TM can originate from various sources. The
selection of the required clock source is implemented using the xTnCK2~xTnCK0 bits in the xTMn
control registers, where “x” stands for C, S or P type TM and “n” stands for the specific TM serial
number. For STM and PTM there is no serial number “n” in the relevant pin or control bits since
there is only one STM and PTM respectively in the series of devices, The clock source can be a ratio
of the system clock, f
SYS
, or the internal high clock, f
H
, the f
SUB
clock source or the external xTCKn
pin. The xTCKn pin clock source is used to allow an external signal to drive the TM as an external
clock source for event counting.
TM Interrupts
The Compact, Standard or Periodic type TM has two internal interrupt, one for each of the internal
comparator A or comparator P, which generate a TM interrupt when a compare match condition
occurs. When a TM interrupt is generated, it can be used to clear the counter and also to change the
state of the TM output pin.
TM External Pins
Each of the TMs, irrespective of what type, has one or two TM input pins, with the label xTCKn and
xTPnI respectively. The xTMn input pin, xTCKn, is essentially a clock source for the xTMn and is
selected using the xTnCK2~xTnCK0 bits in the xTMnC0 register. This external TM input pin allows
an external clock source to drive the internal TM. The xTCKn input pin can be chosen to have either
a rising or falling active edge. The STCK and PTCK pins are also used as the external trigger input
pin in single pulse output mode for the STM and PTM respectively.
The other xTM input pin, STPI or PTPI, is the capture input whose active edge can be a rising edge,
a falling edge or both rising and falling edges and the active edge transition type is selected using
the STIO1~STIO0 or PTIO1~PTIO0 bits in the STMC1 or PTMC1 register respectively. There is
another capture input, PTCK, for PTM capture input mode, which can be used as the external trigger
input source except the PTPI pin.
The TMs each have two output pins, xTPn and xTPnB. The xTPnB is the inverted signal of the
xTPn output. The TM output pins can be selected using the corresponding pin-shared function
selection bits described in the Pin-shared Function section. When the TM is in the Compare Match
Output Mode, these pins can be controlled by the TM to switch to a high or low level or to toggle
when a compare match situation occurs. The external xTPn or xTPnB output pin is also the pin
where the TM generates the PWM output waveform. As the TM output pins are pin-shared with
other functions, the TM output function must first be setup using relevant pin-shared function
selection register.
